1. Field
The disclosure relates to a hydraulic active booster, and more particularly to a hydraulic active booster capable of mechanically separating a control plunger from a piston of a master cylinder in a normal operation mode and rapidly forming braking pressure according to pedal force of a driver in an abnormal operation mode.
2. Description of the Related Art
In general, when a driver steps on a brake pedal, a hydraulic active booster (HAB) detects displacement of the brake pedal from a pedal displacement sensor and closes a shut-off valve to separate a master cylinder of a pedal simulator from a fluid path, and an electronic control unit (ECU) calculates wheel pressure according to a pressure signal of a pressure sensor to control pressure of each wheel through an independent feedback control.
When the HAB fails, the shut-off valve is switched into a normally open (NO) state, so liquid pressure of the master cylinder corresponding to pedal force of the driver is transferred to a wheel cylinder so that the braking operation can be performed upon the system failure.
Meanwhile, the HAB according to the related art includes a simulator having a simulator piston and a simulator spring elastically supporting the simulator piston. Such a simulator is configured to be coupled to an open end of the master cylinder.
As mentioned above, the simulator piston and the simulator spring are installed in the simulator. However, since the simulator piston and the simulator spring are installed in a limited space together with a control plunger, there is difficulty to control the shape and the number of the simulator piston and the simulator spring.